Understanding Your Laboratory Test: What It Is, Why It Is Done, and What to Expect
This test measures the amount of barbital (a barbiturate medication) in your blood to monitor drug levels and ensure safe dosing.
{"Barbital is a barbiturate medication used for sedation and seizure control","This test checks if the drug level in your blood is within the therapeutic range","Regular monitoring helps prevent toxicity and ensures effective treatment","Blood samples are typically collected via venipuncture","Results help healthcare providers adjust dosage as needed"}
Key facts at a glance
- LOINC
- 78804-2
- Short code
- BARB
- Synonyms
- Barbital Bld-mCnc
- Category
- chemistry
- Sample
- whole-blood
- Container
- Gray-top sodium fluoride/potassium oxalate tube or red-top tube (no anticoagulant for serum)
- Units
- N/A
- Ref low
- 0
- Ref high
- 0
- Critical range
- — – 10 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Gas chromatography-mass spectrometry (GC-MS) or immunoassay
- CPT
- 80345
- SNOMED
- 3957900
- Specimen volume
- 5 mL whole blood
- Stability
- Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C
- Hemolysis max
- 100
- Lipemia max
- 50
- Icterus max
- 25
- TAT
- 24–72 hours
- Order
- routine
This test is a diagnostic procedure in which a small sample, such as blood, urine, or tissue, is collected and analyzed in a laboratory. The results help your healthcare provider learn more about how your body is working and support accurate diagnosis.
The Barbital Blood Test measures the concentration of barbital in your whole blood. Barbital is a barbiturate—a class of medications that act as central nervous system depressants. This test is primarily used to monitor patients who are prescribed barbital or other barbiturate medications for conditions such as anxiety, insomnia, or seizure disorders.
Your doctor may order this test to help diagnose a medical condition, check how well an organ is working, monitor an ongoing illness, or see how well a treatment is responding. The results can guide important decisions about your ongoing care.
This test is performed for several important reasons: (1) To ensure the drug level is within the therapeutic range—enough to be effective but not so high as to cause harmful side effects; (2) To monitor patient compliance with medication regimens; (3) To help diagnose potential cases of barbiturate overdose or poisoning; (4) To guide healthcare providers in adjusting dosages for optimal treatment outcomes.
The test is usually performed in a clinic, hospital, or laboratory. A trained technician or nurse will collect the needed sample using standard steps designed to keep you comfortable and safe, and then send it to the laboratory for careful analysis.
A healthcare professional will collect a blood sample from a vein in your arm using a needle and syringe or a collection tube. The sample is then sent to a laboratory for analysis. The procedure is quick and typically takes only a few minutes. You may experience minor discomfort or bruising at the puncture site, but serious complications are rare.
Are there any special preparations needed? In many cases no preparation is required, but some tests call for fasting, avoiding certain medicines, or drinking extra water beforehand. Always follow the specific instructions your healthcare team gives you.
Follow your healthcare provider's instructions regarding medication timing. Inform your doctor about all medications, supplements, and herbal products you are taking, as some substances may interfere with test results. Fasting is usually not required for this test, but always confirm with your healthcare provider beforehand.
Reference range
Negative (not detected) in individuals not taking barbital; therapeutic monitoring ranges vary by clinical contextN/A
No special preparation required. Patient should be advised to inform the clinician of all medications, including over-the-counter drugs, as barbital is a barbiturate.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The Barbital Blood Test has significant clinical importance in therapeutic drug monitoring (TDM). Maintaining appropriate barbital levels is crucial because the drug has a narrow therapeutic index—meaning the difference between a therapeutic dose and a toxic dose is relatively small. Subtherapeutic levels may lead to inadequate control of seizures or anxiety, while elevated levels can cause serious complications including respiratory depression, sedation, confusion, and in severe cases, coma or death. This test helps healthcare providers individualize dosing regimens and ensure patient safety.
Additionally, this test may be used in forensic or emergency settings to evaluate suspected barbiturate intoxication or to monitor patients with a history of substance abuse. It can also be helpful in assessing drug interactions, as other medications may affect barbital metabolism and blood concentrations.
Frequently asked questions
What do the test results mean?
What is the therapeutic range for barbital?
How often should this test be done?
What are the side effects of barbital?
Can other medications affect barbital levels?
Sources
- 1
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- 3
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy